Objective Investigate the changes of intercuspid and intermolar width in nonextraction treatment. Methods 77 nonextraction cases with mild crowed were used in this study, and the intercuspid and intermolar width were measured on the pre - and post - treatment models. The measurement were compared statistically. Results The intercuspid width on the maxillary increased（1.00±1.79）mm, and the intercuspid width on the mandibular increased （0.51±1.66）mm. The intercuspid changes of pre- and post- treatment have significant difference. No significant difference was founded in the intermolar width. Conclusion The intercuspid width increased slightly after nonextraction treatment, and the intermolar width nearly had no change.
